System and method for saving battery power in a patient monitoring system

ABSTRACT

A vital-signs patch for a patient monitoring system is disclosed. The patch consists of a housing that is configured to be worn on the skin of a patient. The housing contains a radio, one or more sensor interfaces, a processor, and a battery. The processor can selectably turn portions of the processor off and on and selectably turn power off and on to at least a portion of the sensor interfaces and radio. The processor includes a timer that, each time the timer times out, will turn all the parts of the processor on and start a new timing period. When the processor receives a signal, the processor will turn off power to at least a portion of the processor and at least a portion of the sensor interfaces.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.12/844,801 filed Jul. 27, 2010, which issued as U.S. Pat. No. 9,017,255on Apr. 28, 2015, which is herein incorporated by reference in itsentirety for all purposes.

BACKGROUND Field

The present disclosure generally relates to systems and methods ofphysiological monitoring, and, in particular, relates to monitoring ofvital signs of patients in hospitals.

Description of the Related Art

Some of the most basic indicators of a person's health are thosephysiological measurements that reflect basic body functions and arecommonly referred to as a person's “vital signs.” The four measurementscommonly considered to be vital signs are body temperature, pulse rate,blood pressure, and respiratory rate. Some clinicians consider oxygensaturation (S₀₂) to be a “fifth vital sign” particularly for pediatricor geriatric cases. Some or all of these measurements may be performedroutinely upon a patient when they arrive at a healthcare facility,whether it is a routine visit to their doctor or arrival at an EmergencyRoom (ER).

Vital signs are frequently taken by a nurse using basic tools includinga thermometer to measure body temperature, a sphygmomanometer to measureblood pressure, and a watch to count the number of breaths or the numberof heart beats in a defined period of time which is then converted to a“per minute” rate. If a patient's pulse is weak, it may not be possibleto detect a pulse by hand and the nurse may use a stethoscope to amplifythe sound of the patient's heart beat so that she can count the beats.Oxygen saturation of the blood is most easily measured with a pulseoximeter.

When a patient is admitted to a hospital, it is common for vital signsto be measured and recorded at regular intervals during the patient'sstay to monitor their condition. A typical interval is 4 hours, whichleads to the undesirable requirement for a nurse to awaken a patient inthe middle of the night to take vital sign measurements.

When a patient is admitted to an ER, it is common for a nurse to do a“triage” assessment of the patient's condition that will determine howquickly the patient receives treatment. During busy times in an ER, apatient who does not appear to have a life-threatening injury may waitfor hours until more-serious cases have been treated. While the patientmay be reassessed at intervals while awaiting treatment, the patient maynot be under observation between these reassessments.

Measuring certain vital signs is normally intrusive at best anddifficult to do on a continuous basis. Measurement of body temperature,for example, is commonly done by placing an oral thermometer under thetongue or placing an infrared thermometer in the ear canal such that thetympanic membrane, which shared blood circulation with the brain, is inthe sensor's field of view. Another method of taking a body temperatureis by placing a thermometer under the arm, referred to as an “axillary”measurement as axilla is the Latin word for armpit. Skin temperature canbe measured using a stick-on strip that may contain panels that changecolor to indicate the temperature of the skin below the strip.

Measurement of respiration is easy for a nurse to do, but relativelycomplicated for equipment to achieve. A method of automaticallymeasuring respiration is to encircle the upper torso with a flexibleband that can detect the physical expansion of the rib cage when apatient inhales. An alternate technique is to measure a high-frequencyelectrical impedance between two electrodes placed on the torso anddetect the change in impedance created when the lungs fill with air. Theelectrodes are typically placed on opposite sides of one or both lungs,resulting in placement on the front and back or on the left and rightsides of the torso, commonly done with adhesive electrodes connected bywires or by using a torso band with multiple electrodes in the strap.

Measurement of pulse is also relatively easy for a nurse to do andintrusive for equipment to achieve. A common automatic method ofmeasuring a pulse is to use an electrocardiograph (ECG or EKG) to detectthe electrical activity of the heart. An EKG machine may use 12electrodes placed at defined points on the body to detect varioussignals associated with the heart function. Another common piece ofequipment is simply called a “heart rate monitor.” Widely sold for usein exercise and training, heart rate monitors commonly consist of atorso band, in which are embedded two electrodes held against the skinand a small electronics package. Such heart rate monitors cancommunicate wirelessly to other equipment such as a small device that isworn like a wristwatch and that can transfer data wirelessly to a PC.

Nurses are expected to provide complete care to an assigned number ofpatients. The workload of a typical nurse is increasing, driven by acombination of a continuing shortage of nurses, an increase in thenumber of formal procedures that must be followed, and an expectation ofincreased documentation. Replacing the manual measurement and logging ofvital signs with a system that measures and records vital signs wouldenable a nurse to spend more time on other activities and avoid thepotential for error that is inherent in any manual procedure.

SUMMARY

For some or all of the reasons listed above, there is a need for ahospital to be able to continuously monitor its patients in differentsettings within the hospital. In addition, it is desirable for thismonitoring to be done with limited interference with a patient'smobility or interfering with their other activities.

Continuous monitoring implies that the sensors that measure thephysiological characteristic of interest remain continuously in place onthe patient. Periodic removal of a sensor, for such things as using thebathroom or showering, usually requires a nurse or other caregiver toreattach the sensor to ensure that the sensor is properly attached andmay require replacement of the sensor each time the sensor is removed.The presence of wires between the sensors and the monitoring equipmentmakes it difficult for a patient to perform their normal activities andmove around the hospital. An analogous situation exists in use of anintravenous (IV) system to continuously administer medication, where thepatient is connected to an IV bag via a tube which remains continuouslyattached to the patient. Even when the IV bag is mounted on a mobilestand without connection to a fixed piece of equipment, this attachedtube poses a significant impediment to a patient in moving around thehospital, changing clothes, and taking a shower.

One solution to the problem of providing continuous monitoring withouthaving wires connecting the patient to separate device is to use abattery-powered wireless device to measure the physiologicalcharacteristics of interest. The useful life of battery-powered devicesis limited, however, by the capacity of the battery compared to thepower consumption of the device. Providing a battery-powered device thatcan monitor the vital signs of a patient for a period of several daysmay require a battery so large that it is impractical for the patient tocontinuously wear the device. It is highly desirable to provide avital-signs monitoring device that has a very low level of powerconsumption such that a very small battery, such as the “coin” batteriescommonly used in watches, has enough power to continuously operate thedevice for several days.

Embodiments of the patient monitoring system disclosed herein measurecertain vital signs of a patient, which include respiratory rate, pulserate, and body temperature, on a regular basis and compare thesemeasurements to preset limits.

In certain embodiments of the disclosure, a vital-signs patch for apatient monitoring system is disclosed. The patch consists of a housingthat is configured to be worn on the skin of a patient. The housingcontains a radio, one or more sensor interfaces, a processor, and abattery. The processor can selectably turn portions of the processor offand on and selectably turn power off and on to at least a portion of thesensor interfaces and radio. The processor includes a timer that, eachtime the timer times out, will turn all the parts of the processor onand start a new timing period. When the processor receives a signal, theprocessor will turn off power to at least a portion of the processor andat least a portion of the sensor interfaces.

In certain embodiments of the disclosure, a patient monitoring system isdisclosed. The system includes a patch configured to turn off a portionof its circuitry for a period of time upon receipt of a sleep signal andthen to turn on that portion of its circuitry after a period of time haselapsed, and a bridge configured to send the sleep signal to the patch.The bridge tracks when the period of time elapses and sends the sleepsignal to the patch after the period of time elapses.

In certain embodiments of the disclosure, a method of conserving batterypower in a patch in a patient monitoring system is disclosed. The methodincludes the steps of the patch receiving a sleep signal, turning off aportion of the circuitry of the patch and starting a timer, turning onthe portion of the circuitry that was turned off upon the timer timingout, and resumption of monitoring for sleep signals.

It is understood that other configurations of the subject technologywill become readily apparent to those skilled in the art from thefollowing detailed description, wherein various configurations of thesubject technology are shown and described by way of illustration. Aswill be realized, the subject technology is capable of other anddifferent configurations and its several details are capable ofmodification in various other respects, all without departing from thescope of the subject technology. Accordingly, the drawings and detaileddescription are to be regarded as illustrative in nature and not asrestrictive.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide furtherunderstanding and are incorporated in and constitute a part of thisspecification, illustrate disclosed embodiments and together with thedescription serve to explain the principles of the disclosedembodiments. In the drawings:

FIG. 1 is a diagram illustrating an exemplary embodiment of a patientmonitoring system according to certain aspects of the presentdisclosure.

FIG. 2A is a perspective view of the vital-signs monitor patch of FIG. 1according to certain aspects of the present disclosure.

FIG. 2B is a cross-section of the vital-signs monitor patch of FIG. 1according to certain aspects of the present disclosure.

FIG. 2C is a functional block diagram illustrating exemplary electronicand sensor components of the vital-signs monitor patch of FIG. 1according to certain aspects of the present disclosure.

FIG. 3A is a functional schematic diagram of the bridge according tocertain aspects of the subject disclosure.

FIG. 3B is a functional schematic diagram of an embodiment of thesurveillance server according to certain aspects of the presentdisclosure.

FIG. 4 discloses an example of the communication protocol between thevital-signs patch and bridge according to certain aspects of the presentdisclosure.

FIG. 5 is a plot of power consumption vs. time illustrating that batterypower in the vital-signs patch is conserved according to certain aspectsof this disclosure.

FIG. 6 is a functional block diagram illustrating exemplary details ofthe processor of FIG. 2C according to certain aspects of the presentdisclosure.

DETAILED DESCRIPTION

Periodic monitoring of patients in a hospital is desirable at least toensure that patients do not suffer an un-noticed sudden deterioration intheir condition or a secondary injury during their stay in the hospital.It is impractical to provide continuous monitoring by a clinician andcumbersome to connect sensors to a patient, which are then connected toa fixed monitoring instrument by wires. Furthermore, systems that soundan alarm when the measured value exceeds a threshold value may soundalarms so often and in situations that are not truly serious that suchalarms are ignored by clinicians.

Measuring vital signs is difficult to do on a continuous basis. Accuratemeasurement of cardiac pulse, for example, can be done using anelectrocardiograph (ECG or EKG) to detect the electrical activity of theheart. An EKG machine may use up to 12 electrodes placed at variouspoints on the body to detect various signals associated with the cardiacfunction. Another common piece of equipment is termed a “heart ratemonitor.” Widely sold for use in exercise and physical training, heartrate monitors may comprise a torso band in which are embedded twoelectrodes held against the skin and a small electronics package. Suchheart rate monitors can communicate wirelessly to other equipment suchas a small device that is worn like a wristwatch and that can transferdata wirelessly to a personal computer (PC).

Monitoring of patients that is referred to as “continuous” is frequentlyperiodic, in that measurements are taken at intervals. In many cases,the process to make a single measurement takes a certain amount of time,such that even back-to-back measurements produce values at an intervalequal to the time that it takes to make the measurement. For the purposeof vital sign measurement, a sequence of repeated measurements can beconsidered to be “continuous” when the vital sign is not likely tochange an amount that is of clinical significance within the intervalbetween measurements. For example, a measurement of blood pressure every10 minutes may be considered “continuous” if it is considered unlikelythat a patient's blood pressure can change by a clinically significantamount within 10 minutes. The interval appropriate for measurements tobe considered continuous may depend on a variety of factors includingthe type of injury or treatment and the patient's medical history.Compared to intervals of 4-8 hours for manual vital sign measurement ina hospital, measurement intervals of 30 minutes to several hours maystill be considered “continuous.”

Certain exemplary embodiments of the present disclosure include a systemthat comprises a vital-signs monitor patch that is attached to thepatient, and a bridge that communicates with monitor patches and linksthem to a central server that processes the data, where the server cansend data and alarms to a hospital system according to algorithms andprotocols defined by the hospital.

The construction of the vital-signs monitor patch is described accordingto certain aspects of the present disclosure. As the patch may be worncontinuously for a period of time that may be several days, as isdescribed in the following disclosure, it is desirable to encapsulatethe components of the patch such that the patient can bathe or showerand engage in their normal activities without degradation of the patchfunction. An exemplary configuration of the construction of the patch toprovide a hermetically sealed enclosure about the electronics isdisclosed.

In the following detailed description, numerous specific details are setforth to provide a full understanding of the present disclosure. It willbe apparent, however, to one ordinarily skilled in the art thatembodiments of the present disclosure may be practiced without some ofthe specific details. In other instances, well-known structures andtechniques have not been shown in detail so as not to obscure thedisclosure.

FIG. 1 discloses a vital sign monitoring system according to certainembodiments of the present disclosure. The vital sign monitoring system12 includes vital-signs monitor patch 20, bridge 40, and surveillanceserver 60 that can send messages or interact with peripheral devicesexemplified by mobile device 90 and workstation 100.

Monitor patch 20 resembles a large adhesive bandage and is applied to apatient 10 when in use. It is preferable to apply the monitor patch 20to the upper chest of the patient 10 although other locations may beappropriate in some circumstances. Monitor patch 20 incorporates one ormore electrodes (not shown) that are in contact with the skin of patient10 to measure vital signs such as cardiac pulse rate and respirationrate. Monitor patch 20 also may include other sensors such as anaccelerometer, temperature sensor, or oxygen saturation sensor tomeasure other characteristics associated with the patient. These othersensors may be internal to the monitor patch 20 or external sensors thatare operably connected to the monitor patch 20 via a cable or wirelessconnection. Monitor patch 20 also includes a wireless transmitter thatcan both transmit and receive signals. This transmitter is preferably ashort-range, low-power radio frequency (RF) device operating in one ofthe unlicensed radio bands. One band in the United States (US) is, forexample, centered at 915 MHz and designated for industrial, scientificand medical (ISM) purposes. An example of an equivalent band in theEuropean Union (EU) is centered at 868 MHz. Other frequencies ofoperation may be possible dependent upon the InternationalTelecommunication Union (ITU), local regulations and interference fromother wireless devices.

Surveillance server 60 may be a standard computer server connected tothe hospital communication network and preferably located in thehospital data center or computer room, although other locations may beemployed. The server 60 stores and processes signals related to theoperation of the patient monitoring system 12 disclosed herein includingthe association of individual monitor patches 20 with patients 10 andmeasurement signals received from multiple monitor patches 20. Hence,although only a single patient 10 and monitor patch 20 are depicted inFIG. 1, the server 60 is able to monitor the monitor patches 20 formultiple patients 10.

Bridge 40 is a device that connects, or “bridges”, between monitor patch20 and server 60. Bridge 40 communicates with monitor patch 20 overcommunication link 30 operating, in these exemplary embodiments, atapproximately 915 MHz and at a power level that enables communicationlink 30 to function up to a distance of approximately 10 meters. It ispreferable to place a bridge 40 in each room and at regular intervalsalong hallways of the healthcare facility where it is desired to providethe ability to communicate with monitor patches 20. Bridge 40 also isable to communicate with server 60 over network link 50 using any of avariety of computer communication systems including hardwired andwireless Ethernet using protocols such as 802.11a/b/g or 802.3af. As thecommunication protocols of communication link 30 and network link 50 maybe very different, bridge 40 provides data buffering and protocolconversion to enable bidirectional signal transmission between monitorpatch 20 and server 60.

While the embodiments illustrated by FIG. 1 employ a bridge 20 toprovide communication link between the monitor patch 20 and the server60, in certain alternative embodiments, the monitor patch 20 may engagein direct wireless communication with the server 60. In such alternativeembodiments, the server 60 itself or a wireless modem connected to theserver 60 may include a wireless communication system to receive datafrom the monitor patch 20.

In use, a monitor patch 20 is applied to a patient 10 by a clinicianwhen it is desirable to continuously monitor basic vital signs ofpatient 10 while patient 10 is, in this embodiment, in a hospital.Monitor patch 20 is intended to remain attached to patient 10 for anextended period of time, for example, up to 5 days in certainembodiments, limited by the battery life of monitor patch 20. In someembodiments, monitor patch 20 is disposable when removed from patient10.

Server 60 executes analytical protocols on the measurement data that itreceives from monitor patch 20 and provides this information toclinicians through external workstations 100, preferably personalcomputers (PCs), laptops, or smart phones, over the hospital network 70.Server 60 may also send messages to mobile devices 90, such as cellphones or pagers, over a mobile device link 80 if a measurement signalexceeds specified parameters. Mobile device link 80 may include thehospital network 70 and internal or external wireless communicationsystems that are capable of sending messages that can be received bymobile devices 90.

FIG. 2A is a perspective view of the vital-signs monitor patch 20 shownin FIG. 1 according to certain aspects of the present disclosure. In theillustrated embodiment, the monitor patch 20 includes component carrier23 comprising a central segment 21 and side segments 22 on opposingsides of the central segment 21. In certain embodiments, the centralsegment 21 is substantially rigid and includes a circuit assembly (24,FIG. 2B) having electronic components and battery mounted to a rigidprinted circuit board (PCB). The side segments 22 are flexible andinclude a flexible conductive circuit (26, FIG. 2B) that connect thecircuit assembly 24 to electrodes 28 disposed at each end of the monitorpatch 20, with side segment 22 on the right shown as being bent upwardsfor purposes of illustration to make one of the electrodes 28 visible inthis view.

FIG. 2B is a cross-sectional view of the vital-signs patch 20 shown inFIGS. 1 and 2A according to certain aspects of the present disclosure.The circuit assembly 24 and flexible conductive circuit 26 describedabove can be seen herein. The flexible conductive circuit 26 operablyconnects the circuit assembly 24 to the electrodes 28. Top and bottomlayers 23 and 27 form a housing 25 that encapsulate circuit assembly 28to provide a water and particulate barrier as well as mechanicalprotection. There are sealing areas on layers 23 and 27 that encirclescircuit assembly 28 and is visible in the cross-section view of FIG. 2Bas areas 29. Layers 23 and 27 are sealed to each other in this area toform a substantially hermetic seal. Within the context of certainaspects of the present disclosure, the term ‘hermetic’ implies that therate of transmission of moisture through the seal is substantially thesame as through the material of the layers that are sealed to eachother, and further implies that the size of particulates that can passthrough the seal are below the size that can have a significant effecton circuit assembly 24. Flexible conductive circuit 26 passes throughportions of sealing areas 29 and the seal between layers 23 and 27 ismaintained by sealing of layers 23 and 27 to flexible circuit assembly28. The layers 23 and 27 are thin and flexible, as is the flexibleconductive circuit 26, allowing the side segment 22 of the monitor patch20 between the electrodes 28 and the circuit assembly 24 to bend asshown in FIG. 2A.

FIG. 2C is a functional block diagram 200 illustrating exemplaryelectronic and sensor components of the monitor patch 20 of FIG. 1according to certain aspects of the present disclosure. The blockdiagram 200 shows a processing and sensor interface module 201 andexternal sensors 232, 234 connected to the module 201. In theillustrated example, the module 201 includes a processor 202, a wirelesstransceiver 207 having a receiver 206 and a transmitter 209, a memory210, a first sensor interface 212, a second sensor interface 214, athird sensor interface 216, and an internal sensor 236 connected to thethird sensor interface 216. The first and second sensor interfaces 212and 214 are connected to the first and second external sensors 232, 234via first and second connection ports 222, 224, respectively. In certainembodiments, some or all of the aforementioned components of the module201 and other components are mounted on a PCB.

Each of the sensor interfaces 212, 214, 216 can include one or moreelectronic components that are configured to generate an excitationsignal or provide DC power for the sensor that the interface isconnected to and/or to condition and digitize a sensor signal from thesensor. For example, the sensor interface can include a signal generatorfor generating an excitation signal or a voltage regulator for providingpower to the sensor. The sensor interface can further include anamplifier for amplifying a sensor signal from the sensor and ananalog-to-digital converter for digitizing the amplified sensor signal.The sensor interface can further include a filter (e.g., a low-pass orbandpass filter) for filtering out spurious noises (e.g., a 60 Hz noisepickup).

The processor 202 is configured to send and receive data (e.g.,digitized signal or control data) to and from the sensor interfaces 212,214, 216 via a bus 204, which can be one or more wire traces on the PCB.Although a bus communication topology is used in this embodiment, someor all communication between discrete components can also be implementedas direct links without departing from the scope of the presentdisclosure. For example, the processor 202 may send data representativeof an excitation signal to the sensor excitation signal generator insidethe sensor interface and receive data representative of the sensorsignal from the sensor interface, over either a bus or direct data linksbetween processor 202 and each of sensor interface 212, 214, and 216.

The processor 202 is also capable of communication with the receiver 206and the transmitter 209 of the wireless transceiver 207 via the bus 204.For example, the processor 202 using the transmitter and receiver 209,206 can transmit and receive data to and from the bridge 40. In certainembodiments, the transmitter 209 includes one or more of a RF signalgenerator (e.g., an oscillator), a modulator (a mixer), and atransmitting antenna; and the receiver 206 includes a demodulator (amixer) and a receiving antenna which may or may not be the same as thetransmitting antenna. In some embodiments, the transmitter 209 mayinclude a digital-to-analog converter configured to receive data fromthe processor 202 and to generate a base signal; and/or the receiver 206may include an analog-to-digital converter configured to digitize ademodulated base signal and output a stream of digitized data to theprocessor 202. In other embodiments, the radio may comprise a directsequence radio, a software-defined radio, or an impulse spread spectrumradio.

The processor 202 may include a general-purpose processor or aspecific-purpose processor for executing instructions and may furtherinclude a memory 219, such as a volatile or non-volatile memory, forstoring data and/or instructions for software programs. Theinstructions, which may be stored in a memory 219 and/or 210, may beexecuted by the processor 202 to control and manage the wirelesstransceiver 207, the sensor interfaces 212, 214, 216, as well as provideother communication and processing functions.

The processor 202 may be a general-purpose microprocessor, amicrocontroller, a Digital Signal Processor (DSP), an ApplicationSpecific Integrated Circuit (ASIC), a Field Programmable Gate Array(FPGA), a Programmable Logic Device (PLD), a controller, a statemachine, gated logic, discrete hardware components, or any othersuitable device or a combination of devices that can performcalculations or other manipulations of information.

Information, such as program instructions, data representative of sensorreadings, preset alarm conditions, threshold limits, may be stored in acomputer or processor readable medium such as a memory internal to theprocessor 202 (e.g., the memory 219) or a memory external to theprocessor 202 (e.g., the memory 210), such as a Random Access Memory(RAM), a flash memory, a Read Only Memory (ROM), a ProgrammableRead-Only Memory (PROM), an Erasable PROM (EPROM), registers, a harddisk, a removable disk, or any other suitable storage device.

In certain embodiments, the internal sensor 236 can be one or moresensors configured to measure certain properties of the processing andsensor interface module 201, such as a board temperature sensorthermally coupled to a PCB. In other embodiments, the internal sensor236 can be one or more sensors configured to measure certain propertiesof the patient 10, such as a motion sensor (e.g., an accelerometer) formeasuring the patient's motion or position with respect to gravity.

The external sensors 232, 234 can include sensors and sensingarrangements that are configured to produce a signal representative ofone or more vital signs of the patient to which the monitor patch 20 isattached. For example, the first external sensor 232 can be a set ofsensing electrodes that are affixed to an exterior surface of themonitor patch 20 and configured to be in contact with the patient formeasuring the patient's respiratory rate, and the second external sensor234 can include a temperature sensing element (e.g., a thermocouple or athermistor or resistive thermal device (RTD)) affixed, either directlyor via an interposing layer, to skin of the patient 10 for measuring thepatient's body temperature. In other embodiments, one or more of theexternal sensors 232, 234 or one or more additional external sensors canmeasure other vital signs of the patient, such as blood pressure, pulserate, or oxygen saturation.

FIG. 3A is a functional block diagram illustrating exemplary electroniccomponents of bridge 40 of FIG. 1 according to certain aspects of thesubject disclosure. Bridge 40 includes a processor 310, radio 320 havinga receiver 322 and a transmitter 324, radio 330 having a receiver 332and a transmitter 334, memory 340, display 345, and network interface350 having a wireless interface 352 and a wired interface 354. In someembodiments, some or all of the aforementioned components of module 300may be integrated into single devices or mounted on PCBs.

Processor 310 is configured to send data to and receive data fromreceiver 322 and transmitter 324 of radio 320, receiver 332 andtransmitter 334 of radio 330 and wireless interface 352 and wiredinterface 354 of network interface 350 via bus 314. In certainembodiments, transmitters 324 and 334 may include a radio frequencysignal generator (oscillator), a modulator, and a transmitting antenna,and the receivers 322 and 332 may include a demodulator and antennawhich may or may not be the same as the transmitting antenna of theradio. In some embodiments, transmitters 324 and 334 may include adigital-to-analog converter configured to convert data received fromprocessor 310 and to generate a base signal, while receivers 322 and 332may include analog-to-digital converters configured to convert ademodulated base signal and sent a digitized data stream to processor310.

Processor 310 may include a general-purpose processor or aspecific-purpose processor for executing instructions and may furtherinclude a memory 312, such as a volatile or non-volatile memory, forstoring data and/or instructions for software programs. Theinstructions, which may be stored in memories 312 or 340, may beexecuted by the processor 310 to control and manage the transceivers320, 330, and 350 as well as provide other communication and processingfunctions.

Processor 310 may be a general-purpose microprocessor, amicrocontroller, a Digital Signal Processor (DSP), an ApplicationSpecific Integrated Circuit (ASIC), a Field Programmable Gate Array(FPGA), a Programmable Logic Device (PLD), a controller, a statemachine, gated logic, discrete hardware components, or any othersuitable device or a combination of devices that can performcalculations or other manipulations of information.

Information such as data representative of sensor readings may be storedin memory 312 internal to processor 310 or in memory 340 external toprocessor 310 which may be a Random Access Memory (RAM), flash memory,Read Only Memory (ROM), Programmable Read Only Memory (PROM), ErasableProgrammable Read Only Memory (EPROM), registers, a hard disk, aremovable disk, a Solid State Memory (SSD), or any other suitablestorage device.

Memory 312 or 340 can also store a list or a database of establishedcommunication links and their corresponding characteristics (e.g.,signal levels) between the bridge 40 and its related monitor patches 20.In the illustrated example of FIG. 3A, the memory 340 external to theprocessor 310 includes such a database 342; alternatively, the memory312 internal to the processor 310 may include such a database.

FIG. 3B is a functional block diagram illustrating exemplary electroniccomponents of server 60 of FIG. 1 according to one aspect of the subjectdisclosure. Server 60 includes a processor 360, memory 370, display 380,and network interface 390 having a wireless interface 392 and a wiredinterface 394. Processor 360 may include a general-purpose processor ora specific-purpose processor for executing instructions and may furtherinclude a memory 362, such as a volatile or non-volatile memory, forstoring data and/or instructions for software programs. Theinstructions, which may be stored in memories 362 or 370, may beexecuted by the processor 360 to control and manage the wireless andwired network interfaces 392, 394 as well as provide other communicationand processing functions.

Processor 360 may be a general-purpose microprocessor, amicrocontroller, a Digital Signal Processor (DSP), an ApplicationSpecific Integrated Circuit (ASIC), a Field Programmable Gate Array(FPGA), a Programmable Logic Device (PLD), a controller, a statemachine, gated logic, discrete hardware components, or any othersuitable device or a combination of devices that can performcalculations or other manipulations of information.

Information such as data representative of sensor readings may be storedin memory 362 internal to processor 360 or in memory 370 external toprocessor 360 which may be a Random Access Memory (RAM), flash memory,Read Only Memory (ROM), Programmable Read Only Memory (PROM), ErasableProgrammable Read Only Memory (EPROM), registers, a hard disk, aremovable disk, a Solid State Memory (SSD), or any other suitablestorage device.

Memory 362 or 370 can also store a database of communication links andtheir corresponding characteristics (e.g., signal levels) betweenmonitor patches 20 and bridges 40. In the illustrated example of FIG.3B, the memory 370 external to the processor 360 includes such adatabase 372; alternatively, the memory 362 internal to the processor360 may include such a database.

FIG. 4 discloses certain aspects of the communication protocol betweenpatch 20 and bridge 40. Bridge 40 may be configured to communicate withmultiple patches 20. Bridge 40 will define a length of time during whichit will allocate time to communicate with each patch 20. This definedperiod of time 420 is termed a ‘frame’ and FIG. 4 illustrates how a datastream 410 is segmented into frames 420 that are sequentially arrangedand numbered. Frame N is preceded by frame N−1 and followed by frameN+1. Each frame 420 has an identical internal structure which, in thisexample, has been configured to enable bridge 40 to communicate with upto eight patches. Frame 420 has been segmented into eight time slots430, numbered 1-8 in this example, as shown in the expanded view offrame 420. Each patch 20 which is in communication with bridge 40 isassigned to a time slot 430 by bridge 40.

FIG. 5 discloses how battery power is conserved according to certainaspects of this disclosure. Plot 500 illustrates the instantaneous powerconsumption of a patch 20, with time plotted on the horizontal axis andpower plotted on the vertical axis. The frame sequence 410 from FIG. 4is repeated as timeline 510 as a reference. In timeline 510, the patch20 whose power is plotted in plot 500 has been assigned to time slot 515which is the first time slot in each frame and is darkened in each frameof timeline 510.

At the beginning of each time slot 430, the entire electronics of patch20 are turned on. Patch 20 sends a very short message announcing that itis awake. When bridge 40 receives this signal, it will send a commandsignal to patch 20. If bridge 40 watches patch 20 to perform anoperation, such as reporting its configuration or status or uploadingmeasurements, bridge 40 sends a command to perform this function. If noaction by patch 20 is desired at this time, bridge 40 sends a ‘sleep’command. Upon receiving a sleep command, patch 20 turns off power to aportion of the electronics including, in this example and referring toFIG. 2C, all power to the transmitter 206, receiver 209, sensorinterfaces 212, 214, and 216 which also removes power from sensors 232,234, and 236. The patch also turns off a portion of the processor 202,which is described in more detail in FIG. 6. Patch 20 remains in thissleep state until the portion of processor 202 that is still on wakes uppatch 20 by turning on the rest of the processor and the otherelectronics that have been turned off. The time of this sleep state isselected such that patch 20 wakes up at the beginning of the next timeslot.

Referring to FIG. 6, processor 202 may have more than one section ofcircuitry that can be independently operated. In this example, there isa high-power section 615, which contains the CPU 610 and memory 219 andis driven by a 16 MHz crystal clock 612, and a low-power section 650,which contains a timer 620 which is driven by a 32 kHz crystal clock630. Section 615 can be turned off by CPU 610. Crystal clocks consumemore power relative than other types of semiconductor devices, and theamount of power consumed by a crystal clock is proportional to thefrequency of the crystal, as a fixed amount of electrical charge isconsumed to switch states at every oscillation. A 16 MHz crystal willusually consume much more power than a 32 kHz crystal as the frequencyof the crystal is 500 times higher. Section 650, in this example,contains low-power fixed-duration hardware timer 620 and low-power clock630.

In this example, timer 620 runs continuously and sends out an‘interrupt’ signal every 8 seconds. If section 615 is off when theinterrupt signal is sent out by timer 620, section 615 turns on and thenCPU 610 sends out commands to turn on the rest of the electroniccomponents of patch 20. The state of patch 20 is termed “awake” whenboth section 615 and section 650 are on and “asleep” when only thelow-power section 650 is on. The power consumption while the patch 20 isawake is higher than the power consumption while patch 20 is asleep.

Referring again to FIG. 5, exemplary power levels of the three states ofpatch 20 are marked on the vertical axis—‘asleep’, ‘awake’ during whichpatch 20 can receive signals, and ‘transmit’ during which patch 20 istransmitting signals to bridge 40. Initially, patch 20 is asleep and thepower consumption level is low. At the beginning of time slot 1 in frameN−2, timer 620 in processor 202 times out and sends out its interrupt,turning on the high-power section 615 of processor 202 and the rest ofthe circuitry of patch 20. This is shown as event 520. Bridge 40 issynchronized with patch 20 and knows that time slot 1 is assigned tothis patch 20. In this example, bridge 40 sends a ‘sleep’ command topatch 20, patch 20 turns off its high-power section and associatedcircuitry and the power level drops back to the initial low level. Patch20 remains asleep until the timer again times out and patch 20 wakes upat event 521. Bridge 40 again sends a ‘sleep’ command. This repeats, inthis example, through events 522 and 523. When patch 20 wakes up atevent 524, however, bridge 40 sends a command to upload storedmeasurement data. This is reflected in the power level of event 524rising to the ‘transmit’ level of power consumption. After the data isreceived, bridge 40 sends a ‘sleep’ command and patch 20 goes to sleep.When patch 20 wakes up at events 525 and 526, the bridge sends a ‘sleep’command.

As timer 620 is running continuously, the interrupt signal that timer620 ends out remains synchronized with frame sequence 410 independent ofhow long patch 20 remains awake in each time slot 430.

As can be seen from plot 510, the average power consumption of patch 20is much lower in this mode of operation that it would be if patch 20 wasawake for the entire time. For the example in which the duration of thetime that patch 20 is awake during events 520-523 and 525-526 is 0.5seconds, and the duration of a frame 420 is 8 seconds, and if the powerconsumption when patch 20 is asleep is 10% of the power consumptionwhile the patch is awake, then the average power consumption of thisconfiguration will be (0.5/8.0)*0.10=0.00625 or approximately 0.6% ofthe power that would be consumed if patch 20 was awake the entire time.It can be seen that implementation of this mode of operation has thepotential to extend the battery life by a factor of more than 100×compared to a similar unit that is continuously awake. This reducedlevel of average power consumption of this example would enable abattery-powered device to operate for 100× longer that a similar unitthat is continuously awake or, alternately, the use of a 100× smallerbattery to provide an equivalent operating life to a similar unit thatis continuously awake. A smaller battery enables the overall size andweight of patch 20 to be smaller which is less intrusive and morecomfortable to the patient 10 who is wearing the patch 20.

It can be seen that the disclosed embodiments of the vital-signs monitorpatch provide a mobile solution to monitoring the vital signs of apatient. The design of the vital-signs monitor patch frees nurses, orother caregivers, from the task of repetitively measuring the vitalsigns of their patients, allowing the caregivers to spend more time onother duties. The ability to continuously monitor a patient's vitalsigns using a monitor patch, together with the rest of the patientmonitoring system, increases the ability of the nurse to respond quicklyto a sudden change in a patient's condition, resulting in improved carefor the patient.

The reduction of power consumption in the vital-signs monitoring patchenables the patch to be smaller and lighter than it would be if thedisclosed features were not utilized. A smaller patch will be morecomfortable to wear and less intrusive in normal activities of thepatient as well as less expensive to manufacture. Increased comfort bythe user and reduced cost to the facility providing the care will resultin an increased likelihood that the device will be used, resulting inimproved patient safety.

The previous description is provided to enable any person skilled in theart to practice the various aspects described herein. While theforegoing has described what are considered to be the best mode and/orother examples, it is understood that various modifications to theseaspects will be readily apparent to those skilled in the art, and thegeneric principles defined herein may be applied to other aspects. Thus,the claims are not intended to be limited to the aspects shown herein,but is to be accorded the full scope consistent with the languageclaims, wherein reference to an element in the singular is not intendedto mean “one and only one” unless specifically so stated, but rather“one or more.” Unless specifically stated otherwise, the term “some”refers to one or more. Pronouns in the masculine (e.g., his) include thefeminine and neuter gender (e.g., her and its) and vice versa. Headingsand subheadings, if any, are used for convenience only and do not limitthe invention.

The term ‘battery’ is intended to encompass all energy storage deviceswhich deliver electricity. These energy storage devices may berechargeable or single-use. This includes but is not limited tobatteries using lead-acid, zinc-carbon, alkaline, nickel cadmium,lithium, and lithium-ion technologies, capacitors, generators powered bysprings or compressed gas or other mechanical energy storage mechanisms,and fuel cells.

Those of skill in the art will appreciate that the various illustrativefunctional bocks, modules, components, methods, and algorithms describedherein may be implemented as hardware, software, or a combination of thetwo. Various components and functional elements may be arranged in adifferent configuration or partitioned in a different way withoutdeparting from the scope of the claimed invention.

It is understood that the specific order or hierarchy of steps in theprocesses disclosed is an illustration of exemplary approaches. Basedupon design preferences, it is understood that the specific order orhierarchy of steps in the processes may be rearranged. Some of the stepsmay be performed simultaneously. The accompanying method claims presentelements of the various steps in a sample order, and are not meant to belimited to the specific order or hierarchy presented.

Terms such as “top,” “bottom,” “front,” “rear” and the like as used inthis disclosure should be understood as referring to an arbitrary frameof reference, rather than to the ordinary gravitational frame ofreference. Thus, a top surface, a bottom surface, a front surface, and arear surface may extend upwardly, downwardly, diagonally, orhorizontally in a gravitational frame of reference.

A phrase such as an “aspect” does not imply that such aspect isessential to the subject technology or that such aspect applies to allconfigurations of the subject technology. A disclosure relating to anaspect may apply to all configurations, or one or more configurations. Aphrase such as an aspect may refer to one or more aspects and viceversa. A phrase such as an “embodiment” does not imply that suchembodiment is essential to the subject technology or that suchembodiment applies to all configurations of the subject technology. Adisclosure relating to an embodiment may apply to all embodiments, orone or more embodiments. A phrase such an embodiment may refer to one ormore embodiments and vice versa.

The word “exemplary” is used herein to mean “serving as an example orillustration.” Any aspect or design described herein as “exemplary” isnot necessarily to be construed as preferred or advantageous over otheraspects or designs.

All structural and functional equivalents to the elements of the variousaspects described throughout this disclosure that are known or latercome to be known to those of ordinary skill in the art are expresslyincorporated herein by reference and are intended to be encompassed bythe claims. Moreover, nothing disclosed herein is intended to bededicated to the public regardless of whether such disclosure isexplicitly recited in the claims. No claim element is to be construedunder the provisions of 35 U.S.C. § 112, sixth paragraph, unless theelement is expressly recited using the phrase “means for” or, in thecase of a method claim, the element is recited using the phrase “stepfor.” Furthermore, to the extent that the term “include,” “have,” or thelike is used in the description or the claims, such term is intended tobe inclusive in a manner similar to the term “comprise” as “comprise” isinterpreted when employed as a transitional word in a claim.

What is claimed is:
 1. A vital-signs monitor for a patient monitoringsystem, comprising: a transceiver configured to transmit and receivewireless signals to a healthcare network; a sensor interface; a patientsensor coupled to the sensor interface, the patient sensor configured tomeasure a property of the patient; an energy storage device; a monitorprocessor connected to the transceiver, the energy storage device, andthe sensor interface, wherein: the monitor processor comprises first andsecond sections and a timer that is configured to time out after aspecified time period and cause to turn on power from the energy storagedevice to the first section of the monitor processor, the sensorinterface, and the transceiver that have been turned off, and start anew timing period; the monitor processor is configured to, upon receiptof a command to upload a stored measurement data, transmit the storedmeasurement data in a pre-selected time slot assigned to the vital-signsmonitor in a frame of a data stream of a bridge device, wherein thetimer is synchronized among a plurality of vital-signs monitors incommunication with the bridge device so that the pre-selected time slotis one among a plurality of time slots in the frame of the data streamassigned to the plurality of vital-signs monitors by the bridge device;and the monitor processor is configured to, upon receipt of a sleepsignal, turn off power from the energy storage device to the firstsection of the monitor processor and turn off power from the energystorage device to the sensor interface and the transceiver, wherein themonitor processor is configured to receive the sleep signal transmittedfrom the bridge device during the pre-selected time slot, wherein thetransceiver, the sensor interface, the energy storage device, thepatient sensor, and the monitor processor are each affixed within or ona housing formed of at least a first layer attached to a second layer bya moisture and particulate resistant seal, wherein the energy storagedevice is suitable for mobile use on a user-worn device based on powermanagement by the monitor processor, wherein the data stream comprises aframe sequence of a plurality of frames, each frame having the sameinternal structure with the same pre-selected time slot for transmittinga signal to the vital-signs monitor, and wherein an interrupt signalsent by the timer remains synchronized with the frame sequenceindependent of how long the vital-signs monitor remains awake in eachpre-selected time slot.
 2. The vital-signs monitor of claim 1, whereinthe timer is configured to time out after a fixed period of time.
 3. Thevital-signs monitor of claim 1, wherein the timer is configured toprovide the interrupt signal as a periodic interrupt signal that turnsthe first section of the monitor processor on when the first section ofthe monitor processor is off.
 4. The vital-signs monitor of claim 3,wherein a second section of the monitor processor puts the first sectionof the monitor processor to sleep at an end of the pre-selected timeslot assigned to the vital-signs monitor.
 5. The vital-signs monitor ofclaim 3, further configured so that a rate of power consumption whilethe first section of the monitor processor is turned off is lower than arate of power consumption while the monitor processor is turned on. 6.The vital-signs monitor of claim 1, further configured to consume powerat a first rate when the transceiver, the sensor interface, and themonitor processor are fully turned on and consume power at a second ratewhen the transceiver, the sensor interface, and the first section of themonitor processor are turned off, wherein the second rate is lower thanthe first rate.
 7. The vital-signs monitor of claim 1, wherein: themonitor processor comprises a first clock and a second clock; the firstclock consumes more power than the second clock; the first section ofthe monitor processor that is turned off comprises the first clock; thesecond section of the monitor processor comprises the second clock; andthe timer is configured to operate from the second clock.
 8. Thevital-signs monitor of claim 1, wherein the timer is configured to runcontinuously and automatically start a new timing period when it timesout, wherein the new timing period is configured to start at thebeginning of the pre-selected time slot of the next frame of theplurality of frames in the data stream of the bridge device.
 9. Thevital-signs monitor of claim 1, wherein the patient sensor is configuredto monitor at least one of an accelerometer, a temperature sensor, or anoxygen saturation sensor.
 10. The vital-signs monitor of claim 1,wherein the patient sensor is an external sensor that is operablycoupled with the vital-signs monitor via one of a cable or a wirelesscoupling.
 11. The vital-signs monitor of claim 1, wherein the sensorinterface comprises an electronic component configured to perform one ofgenerating an excitation signal to a sensor or providing adirect-current (DC) power to a sensor.
 12. The vital-signs monitor ofclaim 1, wherein the sensor interface comprises one of a signalgenerator for generating an excitation signal to the patient sensor, avoltage regulator for providing power to the patient sensor, anamplifier for amplifying a sensor signal from the patient sensor, ananalog-to-digital converter for digitizing an amplified sensor signal,or a filter for filtering out noise from the patient sensor.
 13. Thevital-signs monitor of claim 1, further comprising a printed circuitboard, wherein an internal sensor is mounted on the printed circuitboard and is configured to measure a temperature of the printed circuitboard.
 14. The vital-signs monitor of claim 1, wherein the monitoringprocessor is configured to send configuration information to an externaldevice through the transceiver.